On my team, I always like to see someone go ana (because she OP) or rein (finally, no hog and ball torture).
On the enemy, I love to see a zen. Easy to hit, most of them in my elo have terrible aim, pretty bad heals compared to basically every other healer, and it’s very fun to put them in danger to make them think they need to use their ultimate, run off, come back when the ultimate ends, and then kill them.